WO2007029511A1

WO2007029511A1 - Fluid bearing device

Info

Publication number: WO2007029511A1
Application number: PCT/JP2006/316592
Authority: WO
Inventors: Tatsuo Nakajima; Isao Komori
Original assignee: Ntn Corporation
Priority date: 2005-09-08
Filing date: 2006-08-24
Publication date: 2007-03-15
Also published as: JP2007100950A

Abstract

A fluid bearing device in which holes required to stabilize and maintain a bearing function are formed at high accuracy and at low cost. Axial grooves (7e) are previously formed in one or more portions of the outer circumferential surface of a sleeve-like raw material (7’) constituting a bearing member (7), and a coating film (10) is formed by aggregates of ink (19) in a fine droplet state. This results that the axial grooves (7e) are closed and axial holes are formed. The axial holes can be used as axial paths (11a) through which lubricating oil flows.

Description

Specification

Hydrodynamic bearing device

Technical field

[0001] The present invention relates to a fluid dynamic bearing device.

Background art

[0002] Fluid dynamic bearing devices have features such as high-speed rotation, high rotation accuracy, and low noise. In recent years, the fluid bearing device has been actively used for information devices, such as magnetic disk devices such as HDD and FDD, CD- Polygons mounted on laser beam printers (LBP), etc. for spindle motors mounted on optical disk devices such as RM, CD-R / RW, DVD—ROM / RAM, magneto-optical disk devices such as MD, MM, etc. It is widely used as a bearing for scanner motors, fan motors mounted on personal computers (PCs), etc., or small motors mounted on electrical equipment such as axial fans.

[0003] This type of hydrodynamic bearing device has a hydrodynamic bearing including a hydrodynamic pressure generating section for generating dynamic pressure in a lubricating fluid (for example, lubricating oil) that fills the bearing gap, and a hydrodynamic pressure generating section. It is roughly divided into non-round bearings (bearings whose bearing cross section is a perfect circle).

[0004] In the hydrodynamic bearing device, during operation, the lubricating oil that fills the internal space may become negative pressure in some areas due to various factors. The generation of such negative pressure causes the generation of bubbles in the lubricating oil, the leakage of the lubricating oil, or the generation of vibrations, and causes a decrease in bearing performance. In order to avoid this type of trouble, it is effective to circulate the lubricating fluid inside the bearing device. To achieve such a circulation of the lubricating fluid, an axial hole is formed in the fixed member. A provided bearing device has been proposed (see, for example, Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-Open No. 2003-232353

Disclosure of the invention

Problems to be solved by the invention

[0005] The axial hole in Patent Document 1 described above is obtained by fixing a bearing sleeve having an axial groove on the outer peripheral surface thereof to the inner peripheral surface of the housing by means such as press-fitting and bonding, thereby fixing the outer peripheral surface of the bearing sleeve And the inner peripheral surface of the housing. However, this structure has a bearing Two parts, a sleeve and a housing, are required, which increases the number of parts and assembly man-hours.

[0006] In addition to the above means, the axial hole can be directly formed in the bearing member by, for example, machining. However, this type of axial hole is often a fine hole with a diameter of lmm or less, and it is extremely difficult to form such a fine hole by machining, in order to ensure machining accuracy. However, the increase in processing costs is inevitable.

[0007] Therefore, an object of the present invention is to make it possible to form holes required for stable maintenance of the bearing function with high accuracy and low cost.

Means for solving the problem

[0008] In order to achieve the above object, a hydrodynamic bearing device according to the present invention includes a shaft member, a bearing member having the shaft member inserted into an inner periphery thereof, and an outer peripheral surface of the shaft member and an inner peripheral surface of the bearing member. A radial bearing portion for supporting the shaft member in the radial direction with a lubricating film of a lubricating fluid formed in the radial bearing gap, and a groove formed on the surface of the sleeve-like material constituting the bearing member, It is characterized in that a hole is formed by closing with an aggregate of trace amounts of ink. The directionality of the “groove” here is not particularly limited, and includes both an axial groove and a radial groove.

[0009] A collection of a small amount of ink that closes the groove can be formed, for example, by using a so-called ink jet method in which ink is supplied from a fine nozzle in a non-contact state with the surface of the material constituting the bearing member. . In addition to the ink jet method, as a method for supplying ink in a non-contact state with the bearing member, a nozzleless type ink jet method (nozzleless ink jet method) in which ink droplets are ejected from the ink surface instead of a nozzle, or electrophoresis is used. The method of guiding the ink, the method of ejecting the ink continuously rather than in the form of droplets via the micropipette, or the method of shortening the distance to the fixing surface and causing the ink to land on the fixing surface simultaneously with the ejection Etc. can also be selected.

[0010] In the ink supply method exemplified above, the ink supply amount and the like can be precisely controlled by the program. Therefore, by controlling the ink supply / stop and supply amount according to the program, the ink supply method is surely achieved. The groove can be closed to form a hole. In this case, the formation of the hole does not require two members, the bearing member and the housing, and / or mechanical processing. Therefore, it is possible to reduce the number of parts and the number of assembly steps, and through these, the cost of the bearing device can be reduced.

[0011] The hole can be used as a flow path through which a lubricating fluid fills the internal space of the bearing device. Thus, during operation of the bearing device, the lubricating fluid circulates inside the bearing device through this flow path. Therefore, for example, when a thrust bearing (thrust bearing gap) is provided in the fluid bearing device and negative pressure is generated in the vicinity of the thrust bearing gap during bearing operation, the pressure of the lubricating fluid in the thrust bearing gap through the flow path is low. Therefore, it is possible to maintain the desired bearing performance stably by preventing the generation of bubbles and the leakage of the lubricating fluid that may occur due to the generation of the negative pressure.

[0012] The sleeve-shaped material constituting the bearing member can be formed of sintered metal. In this case, if at least the outer peripheral surface of the sleeve-shaped material is covered with the above-mentioned collection of minute amounts of ink, the leakage of the lubricating fluid from the outer peripheral surface of the bearing member can be prevented and the contamination of the surrounding environment can be avoided. it can.

The method of curing the ink used in the present invention is not particularly limited, and it can be cured by irradiation with, for example, an electron beam or a light beam in addition to thermal curing. Considering the cost and work environment in particular, it is desirable to use a photocurable ink as the ink and to cure the ink by irradiation with light. As a photo-curable ink, in addition to an ultraviolet curable type and an infrared curable type, the ability to use a visible light curable type ink is particularly desirable. .

[0014] As another means for forming the bearing member without increasing the number of parts and the number of assembling steps, a means for inserting a sleeve-like material and injection-molding the housing can be considered. However, if a sleeve-shaped material having a groove on the surface is used as an insert part as it is, the groove is filled with the insert molding, and the flow path of the lubricating fluid cannot be secured. In this regard, if the bearing member is an injection-molded product using the sleeve-like material in which the hole is formed in the above-described manner as an insert part, the sleeve portion having a hole that does not block the hole that functions as a flow path for the lubricating fluid; It can be configured with the housing part located on the outer peripheral side of the sleeve part.

[0015] The hydrodynamic bearing device having the above configuration includes a motor having a stator coil and a rotor magnet. For example, it can be preferably used for a spindle motor for an information device such as an HDD. The invention's effect

As described above, according to the present invention, a fluid dynamic bearing device capable of stably maintaining high bearing performance can be provided at a lower cost.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 conceptually shows a configuration example of a spindle motor for information equipment. This information equipment

The spindle motor is used for a disk drive device such as an HDD, and is opposed to the fluid bearing device 1 and the disk hub 3 attached to the shaft member 2 of the fluid bearing device 1 through, for example, a radial gap. A stator coil 4, a rotor magnet 5, and a bracket 6. The stator coil 4 is attached to the outer periphery of the bracket 6, and the rotor magnet 5 is attached to the inner periphery of the disk hub 3. The disk hub 3 holds one or more disks D such as a magnetic disk on its outer periphery. The hydrodynamic bearing device 1 is mounted on the inner periphery of the bracket 6. When the stator coil 4 is energized, the rotor magnet 5 is rotated by electromagnetic force generated between the stator coil 4 and the rotor magnet 5, and the disk hub 3 and the shaft member 2 are rotated accordingly.

FIG. 2 shows an example of the hydrodynamic bearing device 1 used in the spindle motor. The hydrodynamic bearing device 1 includes a shaft member 2 having a shaft portion 2a at the center of rotation, a sleeve-shaped bearing member 7 into which the shaft portion 2a can be inserted into the inner periphery, a lid member 8 that seals one end opening thereof, A seal member 9 that seals the other end opening is provided as a main constituent member. In the following, for convenience of explanation, the side sealed by the lid member 8 will be described as the lower side, and the opposite side in the axial direction will be described as the upper side.

In the present embodiment, the first radial bearing portion R1 and the second radial bearing portion R2 are separated in the axial direction between the inner peripheral surface 7a of the bearing member 7 and the outer peripheral surface 2al of the shaft portion 2a. Provided. Also, a first thrust bearing portion T1 is provided between the lower end surface 7c of the bearing member 7 and the upper end surface 2bl of the flange portion 2b, and the lower end surface 2b2 of the flange portion 2b and the upper end surface 8bl of the lid member 8 are provided. Between them, a second thrust bearing portion T2 is provided. [0021] The shaft member 2 is formed of a shaft portion 2a formed of a metal material such as stainless steel, and a metal material such as stainless steel provided integrally or separately with the shaft portion 2a, or a resin material. It consists of a flange part 2b. The outer peripheral surface 2al of the shaft portion 2a is provided with two upper and lower regions that are separated from each other in the axial direction as radial bearing surfaces A of the first radial bearing portion R1 and the second radial bearing portion R2. Each of them has, as a dynamic pressure generating portion, for example, a dynamic pressure groove Aa arranged in a herringbone shape and a partition portion Ab that partitions the dynamic pressure groove Aa. In the present embodiment, the upper dynamic pressure groove is formed to be axially asymmetric with respect to the axial center m, and the axial dimension X1 in the upper region from the axial center m is the axial dimension X2 in the lower region. It's getting bigger than that. Therefore, when the shaft member 2 rotates, the lubricating oil pull-in force (bombing force) by the upper dynamic pressure groove is relatively larger than the lower symmetrical dynamic pressure groove. The method for forming the dynamic pressure generating portion is arbitrary, and an appropriate means such as machining such as rolling or cutting, chemical treatment such as etching, or printing (for example, ink jet printing) can be selected.

[0022] The bearing member 7 is a sintered metal obtained by compacting and sintering a metal powder mainly composed of copper, for example, and is formed in a sleeve shape into which the shaft portion 2a can be inserted. As the sintered metal, oil-impregnated sintered metal impregnated with lubricating oil or lubricating grease in advance is used. In addition, the bearing member 7 can be formed of a solid metal material, for example, a soft metal such as brass. The inner peripheral surface 7a of the bearing member 7 is formed as a smooth cylindrical surface without unevenness. The lower end surface 7c is provided with an annular region serving as a thrust bearing surface of the first thrust bearing portion T1, and a plurality of dynamic pressure grooves arranged in a spiral shape, for example, are formed in the annular region as dynamic pressure generating portions. (Not shown).

[0023] An axial groove 7e is formed in one or a plurality of locations on the outer peripheral surface 7d of the bearing member 7. Further, the outer peripheral surface 7d of the bearing member 7 is provided with a coating 10 made of an aggregate of a small amount of ink that seals the surface opening of the outer peripheral surface 7d and covers the entire outer peripheral surface 7d. Yes. The axial groove 7e formed on the outer peripheral surface 7d is closed with the coating 10, and an axial hole is formed between the coating 10 and the inner peripheral surface. This axial hole functions as a flow path (axial flow path) 11a for circulating the lubricating oil filled in the bearing. The process of forming the coating 10 and the axial flow path 11a will be described in detail later. [0024] The lower end opening of the bearing member 7 is sealed with a lid member 8 formed of a metal material or a resin material. The lid member 8 is formed in a bottomed cylindrical shape including a bottom portion 8b and a cylindrical side portion 8a projecting axially upward from the outer diameter side of the bottom portion 8b. The lid member 8 is fixed to the lower end surface 7c of the bearing member 7 by means such as adhesion, and is formed between the lower end surface 7c of the bearing member 7 and the upper end surface 8bl of the lid member 8. The flange portion 2b of the shaft member 2 is accommodated in the space. A thrust bearing surface of the second thrust bearing portion T2 is provided in a partial annular region of the upper end surface 8bl, and a plurality of dynamic arrays arranged, for example, in a spiral shape are provided in the annular region as dynamic pressure generating portions. A pressure groove is formed (not shown).

[0025] The seal member 9 is formed in a ring shape with a metal material or a resin material, and is fixed to the upper end surface 7b of the bearing member 7 by means such as adhesion. The inner peripheral surface 9a of the seal member 9 has a taper-like diameter increasing toward the upper side, and this inner peripheral surface 9a forms a seal space S having a predetermined volume with the outer peripheral surface 2al of the shaft portion 2a. . Lubricating oil as a lubricating fluid is injected into the internal space of the hydrodynamic bearing device 1 sealed with the sealing member 9, and the oil level of the lubricating oil is maintained within the range of the sealing space S in this state.

In the hydrodynamic bearing device 1 having the above-described configuration, when the shaft member 2 rotates, the radial bearing surface A formed at two locations in the axial direction of the outer peripheral surface 2a 1 of the shaft portion 2a is separated from the inner diameter of the bearing member 7. It faces the peripheral surface 7a via a radial bearing gap. As the shaft member 2 rotates, the lubricating oil film formed between the radial bearing gaps is enhanced by the dynamic pressure action of the dynamic pressure groove, and the shaft member 2 is supported in a non-contact manner so as to be rotatable in the radial direction. . As a result, radial bearing portions R1 and R2 that support the shaft member 2 in a non-contact manner so as to be rotatable in the radial direction are formed.

[0027] When the shaft member 2 rotates, the thrust bearing surfaces formed on the lower end surface 7c of the bearing member 7 and the upper end surface 8bl of the lid member 8 are respectively the upper end surface 2bl and the lower end surface 2b2 of the flange portion 2b. And facing through a thrust bearing gap. As the shaft member 2 rotates, the lubricating oil film formed in the thrust bearing gap is enhanced by the dynamic pressure action of the dynamic pressure groove, and the shaft member 2 is non-contact supported so that it can rotate in the thrust direction. Is done. As a result, thrust bearing portions Tl and T2 are formed to support the shaft member 2 in a non-contact manner so as to be rotatable in both thrust directions.

[0028] During the operation of the hydrodynamic bearing device 1, the lubricating oil filled in the internal space is in a part of the region. There may be negative pressure. The generation of such negative pressure causes a decrease in rotational performance due to generation of bubbles, leakage of lubricating oil, or vibration. Therefore, in this embodiment, in order to prevent the generation of local negative pressure, the dynamic pressure groove shape of the upper radial bearing surface A is made axially asymmetric as described above, and the outer peripheral surface 2al of the shaft portion 2a and the bearing The lubricating oil that fills the radial clearance (radial bearing clearance) between the inner peripheral surface 8a of the member 8 is provided with axially downward bombing capability, and the pushed-down lubricating oil is applied to the upper end of the radial bearing clearance. A circulation path 11 is provided to return the oil to the inside of the hydrodynamic bearing device 1 forcibly circulating the lubricating oil.

A circulation path 11 illustrated in FIG. 2 includes an axial flow path 11a formed by closing the outer periphery of an axial groove 7e formed on the outer peripheral surface 7d of the bearing member 7 with a coating 10, and a seal. The first radial flow path 1 1 b formed between the lower end surface 9b of the member 9 and the upper end surface 7b of the bearing member 7, the upper end surface 8al of the lid member 8, and the lower end surface 7b of the bearing member 7 And a second radial flow path 11c formed between the two. In the illustrated example, the first radial flow path l ib is formed on the lower end face 9b of the seal member 9, and the second radial flow path 11c is formed on the upper end face 8al of the lid member 8, respectively. These radial flow paths l lb and 11c may be formed on the opposite surfaces (upper and lower end surfaces 8b and 8c of the bearing member).

Thus, by providing the circulation path 11, during the operation of the hydrodynamic bearing device 1, the thrust bearing gap → second radial flow path l lc → axial flow path l la → first radius Lubricating oil circulates in the bearing device through the path of the directional flow path l lb → the upper end of the radial clearance (radial bearing clearance). As a result, local negative pressure generation of the lubricating oil in the internal space of the hydrodynamic bearing device 1 can be prevented, and high bearing performance can be maintained.

In the above description, the radial bearing surface A is illustrated as being formed on the outer peripheral surface 2al of the shaft portion 2a. However, the radial bearing surface A is formed in the bearing member 7 by means of compression molding or rolling. It can also be formed on the peripheral surface 7a. In addition, the thrust bearing surfaces are illustrated as being formed on the lower end surface 7c of the bearing member 7 and the upper end surface 8bl of the lid member 8, but these are respectively the upper and lower end surfaces 2bl of the flange portion 2b facing each other through the thrust bearing gap. 2b2 can also be formed.

[0032] As described above, the axial groove 7e is provided on the outer peripheral surface 7d of the bearing member 7, and the outer peripheral surface is provided. If 7d is closed with the coating 10, an axial hole can be formed without providing a separate member (housing) for housing the bearing member 7 or without subjecting it to machining. Since this axial hole can be used as the axial flow path 11a through which the lubricating fluid (lubricating oil) flows, even if negative pressure is generated during the operation of the bearing, it is possible to circulate the lubricating oil inside the bearing S . Therefore, it is possible to reduce the number of parts and the number of assembly steps, or to save the trouble of performing high-precision machining, and to provide the high-precision and low-cost circuit 11 that is indispensable for stably maintaining high bearing performance.

[0033] Next, the step of forming the coating film 10 and the axial flow path 1la on the surface of the sintered metal sleeve-shaped material 7 'constituting the bearing member 7 will be described in detail.

[0034] The coating 10 and the axial flow path 11a are a first step of performing a surface treatment on the outer peripheral surface of the sleeve-shaped material 7 ', a second step of supplying ink to the outer peripheral surface, and curing the supplied ink. Formed through the third step.

In the first step, as shown in FIG. 3, a surface treatment is performed on the outer peripheral surface of the sleeve-shaped material 7 ′ in which the axial groove 7 e is formed in advance at one or a plurality of locations in the circumferential direction. It is sufficient that the surface treatment is performed on the outer peripheral surface of the material 7 ′ to which ink is supplied in the second step, specifically, on the outer peripheral surface except for the axial groove 7 e. Of course, surface treatment may be applied to the region where the axial groove 7e is formed, or it may be applied to both end faces. As the surface treatment, a crushing treatment (for example, rotational sizing or barrel treatment), a coupling treatment or the like can be selected. In the surface treated area, the wettability of the ink deteriorates, that is, the surface tension increases. Therefore, the ability to reduce the amount of ink penetrating into the material vacancies when supplying ink in the second step described later or Ink penetration can be prevented.

The material 7 ′ subjected to the surface treatment in the first step is transferred to the third step of curing the ink through the second step of supplying ink to the outer peripheral surface 7 d of the material 7 ′. In this embodiment, as an example of a method for supplying ink to the outer peripheral surface 7d of the material 7 ′, ink is ejected from a nozzle that is not in contact with the material 7 ′ and landed on the outer peripheral surface 7d of the material 7 ′ to be fixed. Then, an ink jet method was used in which the coating 10 was printed and cured.

FIG. 4 shows an outline of an ink jet printing apparatus that performs printing and curing of the coating 10. This printing device has, as a main component, an outer peripheral surface 7 of a rotationally driven material 7 '. One or a plurality of nose heads 15 serving as a printing unit opposed to d, and a curing unit 17 arranged with a circumferential position different from that of the nose head 15 are provided. The nozzle head 15 is provided with a plurality of nozzles 16 for discharging minute droplets of the ink 19 in the axial direction. The curing unit 17 is a light source that emits light for curing the ink 19 supplied to the material 7 ′, and an ultraviolet lamp, for example, is used.

[0038] The material 7 'is inserted into the through-hole in the axial direction (hole into which the shaft portion 2a is inserted at the time of assembly) by inserting a high-rigidity jig 20 made of a metal material or the like, It is rotated by being supported by the support 18. At this time, the outer peripheral surface of the jig 20 and the inner peripheral surface of the material 7 ′ are set to fit so that the material 7 ′ can rotate in synchronization with the jig 20, for example. In the present embodiment, the coating 10 is continuously printed on a plurality of materials 7 ′ connected in series as shown in the illustrated example. Since the jig 20 is inserted even in a state where a plurality of them are connected, the coaxiality of the materials 7 ′ is secured, and variations in the supply accuracy of the ink 19 are prevented. At this time, it is desirable to align the circumferential positions of the axial grooves 7e between the materials 7 '. Of course, the coating 10 may be printed on a single material 7 '.

For example, as shown in FIG. 5, the nozzle head 15 is arranged along the direction between the tangential direction and the normal direction with respect to the surface of the material 7 ′ that is rotationally driven at a fixed position. At this time, the direction of the nozzle head 15 (the ejection direction of the ink 19) Θ is preferably an angle of 20 ° to 60 ° with respect to the tangential direction.

[0040] As the ink 19, for example, a photocurable resin, preferably an ultraviolet curable resin is used as a base resin, and a photopolymerization initiator, an organic solvent, or the like is appropriately blended. As the base resin, radical polymerization monomers, radical polymerization oligomers, cationic polymerization monomers, imide acrylates, or thiol compounds such as cyclic polyene compounds and polythiol compounds should be used. Among these, radical polymerization monomers, radical polymerization oligomers, or cationic polymerization monomers can be preferably used. Further, as the photopolymerization initiator added to these base resins, a radical photopolymerization initiator or a cationic photopolymerization initiator can be preferably used. In addition, the polymerization initiator can be used by mixing not only one type but also two or more types. [0041] In the above configuration, when the material 7 'is rotated in the direction of the arrow (counterclockwise) shown in FIG. 5 and the nozzle 19 also ejects the ink 19 that forms a fine droplet, the ink 19 becomes the material 7'. Land on the outer peripheral surface 7d. When the printed part advances to some extent in the circumferential direction, the printed part reaches the opposite area of the curing part 17 (the third step of curing the ink), and the ink 19 that has been irradiated with ultraviolet rays undergoes a polymerization reaction. Wake up and harden sequentially. Then, when the material 7 ′ rotates, as shown in FIG. 6A, a first layer film 10a composed of an aggregate of the inks 19 is formed on the outer peripheral surface of the material 7 ′.

[0042] Here, in the present embodiment, the nozzle head 15 is arranged along the direction between the tangential direction and the normal direction with respect to the surface of the material 7 ', so that the axial groove 7e is formed in the nose head 15 ( Even when the nozzle 16 reaches the opposite position, the axial groove 7e is partially shielded by the rear corner 7f, and the ink 19 does not land on the deepest part of the axial groove 7e. In the axial groove 7e, the ink 19 lands only on the outer diameter portion of the wall surface on the rotation direction leading side. As a result, the coating 10a of the first layer is intermittently formed at one or a plurality of locations in the circumferential direction (as shown in the example, three locations when three axial grooves 7e are provided in the circumferential direction). A gap 12 is formed between one end 10al of the coating 10a and the corner 7f.

[0043] Subsequently, when the material 7 'is rotated once, a second layer coating 10b composed of an aggregate of inks 19 is formed on the first layer coating 10a. At this time, since one end of the second layer coating 10b is laminated on one end 10al of the first layer coating 1 Oa, the width of the gap 12 is one revolution (after the formation of the first layer coating 10a). Smaller than. Thereafter, when this is repeated, the width of the gap 12 is gradually reduced, and finally, as shown in FIG. 6B, the uppermost film (sixth film 10f in this embodiment) becomes the axial groove 7e. The axial groove 7e is covered with the first layer coating 10a to the sixth layer coating 10f, which is made up of a trace amount of ink, and is axially closed (axial channel 11a). It becomes. At the same time, the outer peripheral surface of the material 7 ′ is covered with a plurality of layers of coatings 10 a to 10 f, and leakage of lubricating oil from the inside of the material 7 ′ through the surface openings is restricted.

[0044] In the above description, the force that forms the coating 10 by rotating the material 7 'six times, the supply amount of the ink 19 is changed 2 to 5 times or 7 times by changing the arrangement of the nozzle head 15 or the like. The film 10 can also be formed by rolling over.

[0045] Further, in the above description, the material 7 'is rotated counterclockwise to form the coating 10 (axial hole). Although the case where it is formed is shown, the coating 10 can also be formed by rotating the material 7 'clockwise. This is because the nose head 15 is arranged along the direction between the tangential direction and the normal direction with respect to the surface of the material 7 ′ that is rotationally driven at a fixed position.

In the above description, the case where the axial flow path 11a and the coating 10 on the outer peripheral surface of the bearing member 7 are formed by ink jet printing is exemplified. However, the radial flow path 1 lb is formed by the same method. The coating 10 can also be formed on the end face of the bearing member 7 (for example, the upper end face 7b) by the same method.

[0047] According to the ink jet printing method as in this embodiment, the second step of supplying the ink 19 and the third step of curing the ink 19 are performed continuously without time lag, so that the efficiency is improved. The coating 10 can be formed, and pre-programming allows the printing range and ink usage to be managed with high accuracy. A shaped coating 10 can be formed.

FIG. 7 shows a second embodiment of the hydrodynamic bearing device 1 having the configuration of the present invention.

The hydrodynamic bearing device 1 shown in FIG. 1 mainly includes a sleeve portion 22 in which the bearing member 21 has the axial flow path 11a formed in the above-described manner, and a housing portion located on the outer peripheral side of the sleeve portion 22. 2 is different from the hydrodynamic bearing device 1 shown in FIG. In this case, the seal member 9 and the lid member 8 are fixed to the inner peripheral surface of the housing portion 23 by means such as adhesion or press fitting. The radial bearing portions Rl and R2 are formed between the inner peripheral surface 22a of the sleeve portion 22 and the outer peripheral surface 2al of the shaft member 2, and the first thrust bearing portion T1 is the lower end surface 22b of the sleeve portion 22. And the upper end surface 2bl of the flange portion 2b.

[0049] The housing part 23 constituting the bearing member 21 is injection-molded with a molten material using the sleeve part 22 as an insert part. For example, resin can be used as the molten material, and crystalline resins such as liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyacetal (POM), polyamide (PA), Alternatively, amorphous resin such as polyphenylsulfone (PPSU), polyethersulfone (PES), polyetherimide (PEI), and polyamideimide (PAI) is used as the base resin, and this is used as a reinforcing material (fibrous, powdery) Or any other suitable fillers such as lubricants and conductive materials can be used. [0050] When the bearing member 21 is formed in a forceful manner, it is necessary to pay attention to the selection of the base resin for the coating 10 formed on the material 7 '. That is, if the base resin constituting the coating 10 has a lower melting point than that of the base resin constituting the housing portion 23, the coating 10 may be melted by heat during S insert molding (injection molding). . Therefore, in this case, the base resin constituting the coating 10 is selected from those having a melting point higher than that of the base resin constituting the housing portion 23. In other words, the housing part 23 is desirably molded using a base resin having a lower melting point than that of the base resin constituting the ink 19 forming the coating film 10.

[0051] In addition, the housing part 23 can be molded from a molten material other than a resin, as long as the material has a lower melting point than the base resin forming the coating 10.

[0052] If a sleeve-shaped material having a groove on the outer peripheral surface is used as an insert part as it is, the groove is carried along with the insert molding, and the axial flow path 11a cannot be secured. On the other hand, if the housing part 23 is injection-molded using the sleeve part 22 in which the axial flow path 11a is formed in the above-described manner as an insert part, the axial flow path 1la is not blocked. Moreover, if it is insert molding, the bearing member of the said aspect can be obtained, suppressing the width | variety of the cost increase by the increase in a number of parts or an assembly man-hour.

[0053] In addition, if the configuration is powerful, another effect can be expected. When assembled in the motor, the bearing member of the fluid bearing device is fixed to the inner periphery of the bracket 6 as shown in Fig. 1, but until it is fixed, the coating 10 becomes the outer peripheral surface. If it breaks, the sleeve 22 and the outside air communicate with each other and oil leakage occurs. On the other hand, as in the present embodiment, if the bearing member 21 is composed of a sleeve portion 22 and a housing portion 23 formed by injection molding using the sleeve portion 22 as an insert portion, the outer peripheral portion of the axial flow passage 11a. It is also possible to avoid the above problems by increasing the strength.

[0054] Since the functions of the other structural members are the same as those of the hydrodynamic bearing device shown in Fig. 2, the same reference numerals are given and redundant description is omitted.

[0055] In the hydrodynamic bearing device 1 described above, the force exemplified for the configuration in which the radial bearing portions Rl and R2 are configured by the dynamic pressure bearings including the dynamic pressure grooves, one or both of the radial bearing portions Rl and R2 are so-called multiple arcs. The bearing may be a step bearing or a non-circular bearing. This In these bearings, a multi-arc surface, a step surface, or a harmonic wave surface is formed on either the outer peripheral surface 2al of the shaft portion 2a or the inner peripheral surface 7a of the bearing member 7 as the dynamic pressure generating portion ( (Not shown).

[0056] In the fluid dynamic bearing device 1 described above, the radial bearing portion is illustrated as being spaced apart in two axial directions such as the radial bearing portions Rl and R2, but the vertical bearings in the axial direction are illustrated. A configuration in which one radial bearing portion is provided over the region may be adopted. In addition, radial bearings can be provided at three or more locations in the axial direction.

[0057] Although illustration is omitted, one or both of the thrust bearing portions T1 and T2 are, for example, a plurality of radial directions in a region that becomes the thrust bearing surfaces of both end surfaces 2bl and 2b2 of the flange portion 2b. It can also be constituted by a so-called step bearing or a so-called wave-type bearing (a step type is a wave type) in which groove-shaped dynamic pressure grooves are provided at predetermined intervals in the circumferential direction.

[0058] In the above, the case where both the radial bearing portions Rl and R2 are configured by dynamic pressure bearings has been described. However, one or both of the radial bearing portions Rl and R2 may be configured by other bearings. You can also. For example, although not shown in the figure, the outer peripheral surface 2al of the shaft member 2 is formed in a perfect circular outer peripheral surface, and the inner peripheral surface 7a of the bearing member 7 facing the outer peripheral surface is a perfect circular inner peripheral surface. Thus, a so-called perfect circle bearing can also be configured.

[0059] Further, the case where the thrust bearing portion is constituted by a dynamic pressure bearing has been described above. By forming one end of the shaft member 2 in a convex spherical shape, a pivot bearing that contacts and supports the shaft member is formed. Tomorrow.

Brief Description of Drawings

FIG. 1 is a schematic diagram showing an example of a motor incorporating a fluid dynamic bearing device.

FIG. 2 is a cross-sectional view showing a first embodiment of a hydrodynamic bearing device according to the present invention.

FIG. 3 is a perspective view showing an example of a material constituting the bearing member.

FIG. 4 is a cross-sectional view showing an example of an ink jet printing apparatus used for forming a film.

FIG. 5 is a schematic diagram showing an arrangement of a printing unit and a curing unit.

6A] is a cross-sectional view showing the coating after one rotation.

FIG. 6B] is a cross-sectional view showing the coating after a plurality of rotations (after 6 rotations). FIG. 7 is a cross-sectional view showing a fluid dynamic bearing device according to a second embodiment of the present invention. Explanation of symbols

1 Fluid bearing device

2 shaft member

2a Shaft

4 Stator coil

5 Rotor magnet

6 Bracket

7, 21 Bearing member

7 '(composing bearing member) material

7e Axial groove

10 coating

11 Circuit

11a Axial flow path

15 Noznore Head,

16 nozzles

17 Curing part

19 ink

22 Sleeve part

23 Housing part

R1, R2 Radial bearing

T1, T2 Thrust bearing

S Seal space

Claims

The scope of the claims

[1] A shaft member, a bearing member in which the shaft member is inserted into the inner periphery, and a lubricating fluid lubricating film formed in a radial bearing gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member A hydrodynamic bearing device including a radial bearing portion that supports the bearing in a radial direction,

A hydrodynamic bearing device, wherein a hole is formed by closing a groove formed on a surface of a sleeve-shaped material constituting a bearing member with an aggregate of a small amount of ink.

2. The hydrodynamic bearing device according to claim 1, wherein the hole serves as a flow path for a lubricating fluid.

[3] The hydrodynamic bearing device according to claim 1, wherein the sleeve-shaped material is made of sintered metal, and at least an outer peripheral surface of the sleeve-shaped material is covered with an aggregate of a small amount of ink.

4. The hydrodynamic bearing device according to claim 1, wherein the ink has photocurability.

5. The hydrodynamic bearing device according to claim 1, wherein the bearing member is an injection-molded product using the sleeve-shaped material having the hole as an insert portion.

6. A motor comprising the hydrodynamic bearing device according to any one of claims 1 to 5, a stator coil, and a rotor magnet.